Hydrothermal Prepared Bramble-like Double Arrays NiCo₂S₄ Bifunctional Electrocatalysts for High-Efficiency Water Splitting

For highly efficient water-splitting techniques, excellent catalytic activities of noble metal catalysts originate from their material properties, while nonprecious metal catalysts depend on their structural modulation as well as larger exposure zones with more active sites for exhibiting excellent catalytical ability. In this work, we prepared a bramble-like three-dimensional NiCo 2 S 4 nano thorn array homogeneously grown on a nanowire array as precursors and adopted nickel foam as a carrier via a facile hydrothermal method. Owing to its 3D bramble nanowire structure with quick electron transfer ability and larger exposure active sites, this NiCo 2 S 4 composite with dual nanowires exhibited efficient bifunctional catalytic activity and good stability in the electrocatalytic process. It showed remarkable catalytic activity in decomposition water and outputted an HER overpotential at 86 mV at the present density of 10 mA cm –2 as well as an OER overpotential of 203 mV in an alkaline solution. In addition, the unique 3D composited catalyst showed good stability in 1.0 M NaOH solution electrolyte solution and has 72 h with 5000 consecutive cycles without decay at a fixed current density of 10 mA cm –2 . This work might introduce some ideas for the development of transition metal sulfides in the electrochemical breakdown of water and supply a preparation strategy for enlarging the catalytic activities of nonprecious metal catalysts by simply modifying their microstructure.